<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="ajaxBtn">网络请求</button>
    <script>
         window.onerror = function (message, url, line, column, error) {
                console.log('window.onerror 捕获到错误:',message, "==line:", line,"==column:", column, "==error:",error);
        }

        window.addEventListener("error", function(e){
            console.log("window.addEventListener:",e,"==e.error:",e.error);

        },true);

        function test() {
                var xhrObj = new XMLHttpRequest();
                xhrObj.onreadystatechange = function () {
                    console.log("xhrObj.status==",xhrObj.status);
                    if (xhrObj.readyState == 4 && xhrObj.status == 200) {
                        console.log("成功");
                    }
                };

                xhrObj.onerror = function (e) {
                    console.log("-------onerror-------:",e)
                };

                xhrObj.open("post", "http://127.0.0.1:3000/xhr", true);

                xhrObj.send("xhr=1");
            }

            ajaxBtn.onclick=()=>{
                test();
            }
    </script>
</body>
</html>